This invention relates to an information recording apparatus and method, an information reproduction method and apparatus, and an information recording medium suitable for use where various data are recorded onto a recording medium such as a magnetic tape or a magnetic disk as a storage device for a computer.
Conventional information reproduction apparatus such as a hard disk apparatus cannot eliminate appearance of an error at a fixed rate in data reproduced from a recording medium. Therefore, an apparatus of the type mentioned sets a sector length which is a unit of recording and reproduction and an error correction code length in accordance with a characteristic of data.
Since a computer frequently processes a file of a comparatively small size and is required to quickly access various files recorded discretely on a recording medium, it is required to have a high random access performance (hereinafter referred to as random access capability).
Therefore, a magnetic disk apparatus used as a storage device for a computer divides data to be used for recording and/or reproduction into blocks each including a short unit of data and processes the data for the individual blocks (or in other words, sectors of a reduced sector length) to assure a high random access capability. Further, when necessary, the magnetic disk apparatus repeats a retrying operation to compensate for the error correction capability which is deteriorated by the reduction of the sector length so that data can be reproduced with a high degree of reliability.
On the other hand, audio data and/or video data (hereinafter referred to as AV data) are recorded in a comparatively large continuous file on a recording medium, and it is required that the continuous data be reproduced on the real time basis.
Therefore, a data storage apparatus for a video apparatus such as a digital video tape recorder handles data of a comparatively large sector length to effectively prevent an increase in redundancy and strengthen the error correction capability so that data can be successively reproduced with a high degree of reliability.
FIG. 3 shows a magnetic disk apparatus used as a storage apparatus for a computer and employing a hard disk. Referring to FIG. 3, the magnetic disk apparatus 1 shown includes a recording and reproduction circuit 2 which is controlled by a controller 3 and converts, upon recording, data trains outputted from the controller 3 into a serial data train to produce a magnetic head driving signal REC to be used for driving a magnetic head not shown. Upon reproduction, the recording and reproduction circuit 2 processes a reproduction signal PB outputted from the magnetic head to reproduce data recorded on the hard disk and outputs the reproduced data to the controller 3. In the operation of the magnetic disk apparatus 1 described, an error appears at a fixed rate in the data.
A central processing unit (CPU) 4 receives a control command transmitted from a host computer not shown through the controller 3 and controls operation of the controller 3 in accordance with the control command. The central processing unit 4 thus controls operation of the entire magnetic disk apparatus 1 so that a file of the data train outputted from the host computer may be recorded onto the hard disk and conversely a file designated from the host computer may be reproduced from the hard disk.
In the control, the central processing unit 4 confirms a free area of the hard disk and other necessary information from management data recorded in the innermost circumferential record area of the hard disk to control a sequence of operations, and, when necessary, transmits status data corresponding to the control command to the host computer through the controller 3.
A random access memory (RAM) 5 temporarily stores data outputted from the controller 3 and outputs the data to the controller 3 to buffer data D1 to be inputted to or outputted from the host computer through the controller 3.
The controller 3 receives the data D1 outputted from the host computer and transmits data of a control command included in the data D1 to the central processing unit 4. The controller 3 converts those data included in the data D1 which should be recorded into data of a format suitable for recording onto the hard disk and outputs the resulting data to the recording and reproduction circuit 2 under the control of the central processing unit 4.
Further, the controller 3 transmits, from data inputted thereto from the recording and reproduction circuit 2, management data which have been reproduced from the innermost circumferential record area of the hard disk, to the central processing unit 4 so that the central processing unit 4 can access the hard disk in accordance with the management data. The controller 3 processes, from the data inputted thereto from the recording and reproduction circuit 2 in this manner, data of a file designated by the central processing unit 4 reversely to that in the processing performed upon recording and outputs resulting data to the host computer.
Further, the controller 3 outputs status data outputted from the central processing unit 4 to the host computer and outputs management data to the recording and reproduction circuit 2. The controller 3 thus accesses a desired sector of the hard disk and records management data necessary for the accessing to the innermost circumferential record area of the hard disk.
In the processes described above, the controller 3 converts recording data inputted thereto from the host computer into blocks, for example, in a unit of 512 bytes and adds an error correction code of 21 bytes to each block. The controller 3 executes recording and/or reproduction processing in a unit of a block of 512+21 bytes produced in this manner.
More particularly, in the controller 3, a host interface 7 forms an input/output interface with the host computer, and receives data D1 to be recorded from the host computer and outputs the data D1 to a bus controller 8. Conversely, the host interface 7 outputs data D1 reproduced from the hard disk and outputted from the bus controller 8 to the host computer. Further, the host interface 7 outputs a control command inputted thereto from the host computer to the central processing unit 4, but outputs status data outputted from the central processing unit 4 to the host computer.
The bus controller 8 receives data D1 to be recorded from the host interface 7 and temporarily stores the data D1 into the random access memory 5. The bus controller 8 reads out the data D1 stored in the random access memory 5 in this manner in a unit of 512 bytes and outputs the data D1 to a C1 code processing circuit 9 under the control of a sequencer 10.
The bus controller 8 conversely receives, upon reproduction, data D1 reproduced in a unit of 512 bytes from the C1 code processing circuit 9 under the control of the sequencer 10 and temporarily stores the data D1 into the random access memory 5. The bus controller 8 reads out the data D1 temporarily stored in the random access memory 5 in response to processing of the host interface 7 and outputs the data D1 to the host interface 7. If a retry mode is set by the sequencer 10, then the bus controller 8 updates the data stored in the random access memory 5 with the data D1 outputted from the C1 code processing circuit 9. Consequently, the data D1 stored in the random access memory 5 are updated with the data D1 reproduced correctly by the retrying operation, and the correct data D1 are outputted. Further, the bus controller 8 processes management data to be outputted to or inputted from the central processing unit 4 similarly to the data to be outputted to or inputted from the host interface 7.
The C1 code processing circuit 9 produces, upon recording, an error correction code (C1 code) of 21 bytes for the data D1 outputted in a unit of 512 bytes from the bus controller 8, adds the error correction code to the data D1 of 512 bytes and outputs resulting data to a disk controller 11. Upon reproduction, the C1 code processing circuit 9 performs error correction processing for data D1 inputted thereto from the disk controller 11 and having an error correction code added thereto and outputs resulting data to the bus controller 8. Thereupon, the C1 code processing circuit 9 transmits a notification of a result of the error correction processing to the sequencer 10.
Upon recording, the disk controller 11 adds data of a header to data inputted thereto in a unit of 512+21 bytes from the C1 code processing circuit 9 and outputs resulting data to the recording and reproduction circuit 2 under the control of the sequencer 10. On the other hand, upon reproduction, the C1 code processing circuit 9 receives reproduction data of the data recorded in this manner from the recording and reproduction circuit 2 and outputs the reproduction data to the C1 code processing circuit 9. Consequently, the magnetic disk apparatus 1 can record or reproduce desired data in a unit of a sector which is formed from data of 512+21 bytes.
The sequencer 10 is a controller for controlling operation of the controller 3 and controls operation timings of the circuit blocks to control operation of the entire magnetic disk apparatus 1 so that a desired sector of the hard disk may be accessed. In the sequence of processing operations, upon reproduction, the sequencer 10 receives a notification of a result of error correction processing from the C1 code processing circuit 9, and controls operation of the entire magnetic disk apparatus 1 such that, if it detects an error in a reproduced sector, it changes over the mode of the magnetic disk apparatus 1 to a retry mode so that the sector is reproduced repetitively until no error is detected within a preset number of times of retrying operations.
The magnetic disk apparatus 1 thus has a high random access capability and can reproduce data with a high degree of reliability.
FIG. 4 shows a magnetic disk apparatus for recording and reproducing image data, audio data and so forth. Referring to FIG. 4, the magnetic disk apparatus shown is denoted at 21 and includes several similar components to those of the magnetic disk apparatus 1 described hereinabove with reference to FIG. 3. The similar components are denoted by like reference numerals in FIG. 4 and overlapping description of them is omitted here to avoid redundancy.
The magnetic disk apparatus 21 includes a controller 3A which accesses a hard disk and communicates data with a host computer similarly to the controller 3 described above. In such accessing or communication, the controller 3A sets the sector length, for example, to several tens kilobytes and accesses the hard disk in a unit of several tens kilobytes of data. The magnetic disk apparatus 21 further includes a random access memory (RAM) 5A formed from a memory of a large capacity corresponding to the unit in recording and reproduction.
Thus, a bus controller 8A of the controller 3A temporarily stores, upon recording, AV data inputted thereto from the host computer into the random access memory 5A through a host interface 7, reads out the AV data in a unit of a data amount corresponding to the unit in recording and reproduction from the random access memory 5A under the control of a sequencer 10A, and outputs the AV data to a C1 code processing circuit 9A and a C2 code processing circuit 22. In this instance, the bus controller 8A reads out the AV data temporarily stored in the random access memory 5A in a predetermined sequence, shuffles the data to be recorded in the unit in recording and reproduction and outputs resulting data.
Upon reproduction, operation proceeds conversely. In particular, error-corrected AV data outputted from the C2 code processing circuit 22 are temporarily stored into the random access memory 5A and outputted to the host interface 7. The bus controller 8A deshuffles the reproduced AV data conversely to that upon recording and stores resulting data into the random access memory 5A.
The C2 code processing circuit 22 produces, upon recording, a C2 code, which is an outer code of an error correction code of the product code type, based on data inputted thereto from the bus controller 8A, and outputs the thus produced C2 code. Upon reproduction, the C2 code processing circuit 22 performs error correction processing for AV data outputted from the C1 code processing circuit 9A with a C2 code added in this manner and outputs resulting data.
Upon recording, the C1 code processing circuit 9A produces a C1 code, which is an inner code, for AV data inputted thereto from the bus controller 8A and a C2 code outputted from the C2 code processing circuit 22 and outputs the thus produced C1 code to a disk controller 1A. Upon reproduction, the C1 code processing circuit 9A receives AV data outputted from the disk controller 11A, performs error correction processing for the AV data with a C1 code added to the AV data and outputs resulting data to the C2 code processing circuit 22. Thereupon, the C1 code processing circuit 9A transmits a notification of a result of the error correction processing to the sequencer 10A.
The disk controller 11A delimits AV data of one sector length of a unit of several tens kilobytes with a data unit corresponding to a physical sector of the hard disk, adds a header to each of the delimited data units and outputs resulting data. Further, the disk controller 11A outputs AV data inputted thereto from the recording and reproduction circuit 2 to the C1 code processing circuit 9A.
The sequencer 10A is a controller for controlling operation of the controller 3A and controls timings of the circuit blocks to control operation of the entire magnetic disk apparatus 21 so that a desired sector of the hard disk may be accessed. In the sequence of processing operations, upon reproduction, if an error which is difficult to correct with a C2 code in a recording unit of reproduced data is detected based on a notification of a result of error correction processing received from the C1 code processing circuit 9A, the sequencer 10A changes over the operation mode of the entire magnetic disk apparatus 21 to a retry mode and controls the operation of the entire magnetic disk apparatus 21 so that the corresponding sector may be repetitively reproduced until no error is detected within a range of a predetermined set number of times of retrying operations.
In the control described above, since the sequencer 10A has an error correction capability strengthened with an error correction code of the product code type, the number of times of retrying operations is reduced significantly from that by the sequencer 10 described hereinabove with reference to FIG. 3. If correction of an error by a number of times of retrying operations within the predetermined number of retrying operations is difficult, then a notification representing this is transmitted to the host computer through the central processing unit 4. Where AV data are involved, even if error correction is difficult in this manner, it is possible to make use of interpolation processing with data preceding and following the error to substantially make it difficult for a user to perceive the error. This allows the magnetic disk apparatus 21 to reproduce AV data on the real time basis.
Also when AV data are reproduced, random access capability is required upon search and so forth. In this instance, the sector length can be set shorter as in the case of processing of a computer file so that a comparatively small amount of data may be read out from the hard disk to reproduce AV data thereby to augment the random access capability.
In this instance, however, since the sector length is reduced, a retrying operation must be repeated by a greater number of times, and the real time capability is deteriorated as much.
One of possible solutions to this problem is to make the sector length shorter and add an error correction code of the product code type to strengthen the error correction capability and reduce the number of times of retrying operations. However, this solution significantly increases the redundancy and disables effective utilization of an information recording surface of the hard disk.
Thus, a conventional apparatus of the type described is disadvantageous in that it is difficult to satisfy both of the random access capability and the real time performance.
It is an object of the present invention to provide an information recording apparatus and method, an information reproduction apparatus and method and an information recording medium which satisfy both of the random access capability and the real time performance.
In order to attain the object described above, the present invention adopts a countermeasure by which blocks each including a first error correction code for a predetermined unit amount of data and blocks each including a second error correction code for a plurality of such blocks can be reproduced independently of each other such that, when necessary, error correction processing may be performed using the second error correction codes thereby to satisfy both of the real time performance and the random access capability.
In particular, according to the first aspect of the present invention, there is provided an information recording apparatus for recording various data onto a recording medium, comprising first error correction code processing means for delimiting the data in a unit of a predetermined data amount in a time series and successively adding a first error correction code to each of the data of the predetermined data amount to successively form first blocks each of which includes the data of the predetermined data amount and the first error correction code, second error correction code processing means for successively producing a second error correction code for the data of each predetermined number of the first blocks to successively form second blocks whose unit data amount is equal to the data amount of each first block, and means for successively recording the first and second blocks onto the recording medium such that the first and second blocks can be reproduced independently of each other from the recording medium.
According to another aspect of the present invention, there is provided an information recording method for recording various data onto a recording medium, comprising the steps of delimiting the data in a unit of a predetermined data amount in a time series and successively adding a first error correction code to each of the data of the predetermined data amount to successively form first blocks each of which includes the data of the predetermined data amount and the first error correction code, successively producing a second error correction code for the data of each predetermined number of the first blocks to successively form second blocks whose unit data amount is equal to the data amount of each first block, and successively recording the first and second blocks onto the recording medium such that the first and second blocks can be reproduced independently of each other from the recording medium.
According to a further aspect of the present invention, there is provided an information reproduction apparatus for reproducing data recorded on a recording medium, the data including first blocks and second blocks recorded successively on the recording medium, each of the first blocks including delimited object data of a predetermined data amount unit and a first error correction code added to the delimited object data, the first blocks being recorded in a time series on the recording medium, each of the second blocks including a second error correction code for the data of each predetermined number of the first blocks and having a unit data amount equal to the data amount of each first block, the information reproduction apparatus includes mode setting means for selectively setting an operation mode of the information reproduction apparatus between a first operation mode in which the data recorded on the recording medium should be reproduced by error correction processing utilizing the first and second error correction codes and a second operation mode in which the data recorded on the recording medium should be reproduced by error correction processing utilizing the first error correction codes, and reproduction means for reproducing the data recorded on the recording medium in the operation mode set by the mode setting means.
According to a still further aspect of the present invention, there is provided an information reproduction method for reproducing data recorded on a recording medium, the data including first blocks and second blocks recorded successively on the recording medium, each of the first blocks including delimited object data of a predetermined data amount unit and a first error correction code added to the delimited object data, the first blocks being recorded in a time series on the recording medium, each of the second blocks including a second error correction code for the data of each predetermined number of the first blocks and having a unit data amount equal to the data amount of each first block, the information reproduction method includes the steps of selectively setting an operation mode between a first operation mode in which the data recorded on the recording medium should be reproduced by error correction processing utilizing the first and second error correction codes and a second operation mode in which the data recorded on the recording medium should be reproduced by error correction processing utilizing the first error correction codes, and reproducing the data recorded on the recording medium in the set operation mode.
According to a yet further aspect of the present invention, there is provided an information recording medium on which data are recorded, the data including first blocks and second blocks recorded successively on the recording medium such that the first and second blocks can be reproduced independently of each other, each of the first blocks including delimited object data of a predetermined data amount unit and a first error correction code added to the delimited object data, the first blocks being recorded in a time series on the recording medium, each of the second blocks including a second error correction code for the data of each predetermined number of the first blocks and having a unit data amount equal to the data amount of each first block.
With the information recording apparatus and method, the information reproduction apparatus and method and the information recording medium according to the present invention, first blocks each of which includes a first error correction code for data of a unit of a predetermined data amount and second blocks each of which includes a second error correction code for the data of each predetermined number of the first blocks are recorded in such a manner that they can be reproduced independently of each other. Consequently, it is possible to use a small sector length which is a minimum unit of recording and reproduction with first error correction codes and form second error correction codes as independent sectors. Thus, for example, for a data file of a comparatively small size which is used frequently by a computer, a high random access capability can be assured by reproducing the data of the first blocks each of which includes data of the predetermined data amount and the first error correction code. On the other hand, for example, for a file of a comparatively large size such as an AV data file, by reproducing the data of the first blocks and the second blocks each of which includes a second error code for the data of the predetermined number of first blocks, a high error correction capability can be assured while preventing an increase in redundancy, and consequently, a high real time performance can be assured. As a result, when necessary, error correction processing can be performed only with the first error correction codes to give priority to the random access capability, or alternatively, error correction processing can be performed with the first and second error correction codes to give priority to the real time performance. Consequently, both of the real time performance and the random access capability can be satisfied. Accordingly, data files which are frequently used by a computer and for which a high random access capability is required and data files which are frequently used for video data and so forth and for which the real time performance is required can be recorded in a mixed condition onto a recording medium and can be selectively reproduced from the recording medium. This assures a high degree of convenience in use of the recording medium.